I. Field of the Invention
The present invention relates to an iron preparation having a high iron concentration, which is superior in taste and which baby pigs up to 15 days old can ingest easily for nourishment as a feed for baby pigs of the suckling stage; and to a process for preparing such an iron preparation as well as to a method of breeding baby pigs.
II. Description of the Prior Art
Although present in animals in the spleen, liver, kidney and the like, iron is present primarily in hemoglobins and plays an important role in transporting oxygen and carbon dioxide. It is also a constituent of porphyrin proteins, e.g., hemoglobin, myoglobin, cytochrome, catalase, peroxidase and the like and enters into the respiration process.
Generally, baby pigs fall into a state of anemia as their erythrocytes decrease after about the third day after birth. If this state is allowed to continue, the rate of breeding and immunity against disease decrease, whereby the baby pigs become susceptible to disease and death.
This occurs because baby pigs have very small amounts of iron in their tissues at the time of birth, the milk of sows also contains only a small amount of iron, and the hematogenous functions cannot keep up with the very fast growth of the baby pig.
Although at the time of birth the body of a baby pig contains about 15 mg of stored iron which is available for immediate utilization, it consumes about 7 mg of iron every day for making blood. Sow's milk which is the replenishment source of iron contains about 2 mg of iron per liter; however, baby pigs consume only about 500 to 600 ml per day, so that the amount of iron which can be replenished by the sow's milk is no more than about 1 mg per day. Accordingly, as the amount of iron the baby pig requires cannot be completely replenished by the sow's milk, the baby pig depletes its store of iron in three days after birth, causing certain nutritive anemia. In this case, even if large doses of iron supplement were given to the sow, the iron is little tranferred to the sow's milk and no replenishing effect for the baby pigs is achieved.
As a measure of preventing anemia, baby pigs are usually injected with iron preparations in two periods; between the 3rd and 7th day, and between the 10th day and the 14th day after birth. The injection, however, involves the following problems:
1. The operation is laborious because injections must be administered to each individual baby pig. PA1 2. Trauma to the baby pigs may be so great as to hinder their growth. PA1 3. There is possibility of fatal poisoning of the baby pigs. PA1 4. Fevers or tumors may be caused, and degeneration of muscles at the injection site may cripple the animal. PA1 5. If iron is not absorbed in the muscle and remains unabsorbed at the injection site, it may cause discoloration and reduce the quality of the meat.
The absorption of iron through the wall of the intestinal tract is affected by the amount of iron in the body. When the amount of iron is small, the absorption is automatically accelerated. When the amount of iron is sufficient, the absorption of iron is suppressed. Accordingly, where an iron preparation is administered orally, the control function of the absorption of iron in the intestinal tract prevents overabsorption of iron, which protects against poisoning.
Although iron can be absorbed anywhere in the stomach and intestines, it is absorbed mostly through the duodenum. The iron which is absorbed in the intestinal tract is in divalent form. It is considered that, although the iron in feed and organic iron bound loosely to an organic acid is in trivalent form, it is absorbed after reduction to the divalent form by the influence of gastric juices.
It is accordingly ideal that the replenishment of iron in anemic baby pigs be effected through oral administration of iron-supplemented feeds, feed additives or vitamin compositions, and that the iron be absorbed in a natural condition through feed ingestion.
Heretofore, attempts have been made to develop iron-containing feeds or oral preparations for baby pigs of the suckling stage, which have been prepared by admixing iron preparations with a base, such as saccharides, grains, rice bran, wheat bran and the like, and forming the admixture into blocks, fine granules or powders. These attemts, however, have proved fruitless because baby pigs refused to ingest these oral preparations. As iron preparations which are currently available as feed additives, iron sulfate, ferrous fumarate, sodium iron succinate citrate and iron DL-threonine were approved on Sept. 15, 1978, and iron citrate was approved on Nov. 19, 1979, in Japan.